The question as to whether human tumors cary distinctive antigens on their cell surfaces remains the fundamental question of human tumor immunology. One way of analyzing the problem is to capture the ability of lymphocytes from patients and normal individuals to make antibodies reacting with tumor cells. Using hybridoma and EBV-transformation techniques our Laboratories have produced a series of human monoclonal antibodies (hmoAbs) that selectively react with tumor cells. The goal of this project is to isolate and chemically identify some of the antigens identified by these hmoAbs, specifically those that are glycolipids. This will help in understanding tumor antigens and the immune response to them. Two hmoAbs developed from lymphocytes of melanoma patients have been shown to react with NeuAc-type GM3 and GD3 gangliosides. Another two antibodies recognize N-glycolyl-type GM3 and GD3. All four moAbs react with other species of gangliosides still to be characterized. The first two antibodies will be compared with two mouse moABs reacting with the same glycolipids. A number of new hmoAbs developed from the lymphocytes of lung cancer patients that appear to recognize novel neutral glycolipids, as well as those derived from GM2- immunized patients will also be analyzed. Lipids will be extracted from cultured cells, tumors and animal erythrocytes and fractionated by standard techniques into glycolipid fractions whichwill be further purified. The detailed chemical structure of each antigen will be determined by the procedures outlined in the Application. 252Cf fission fragment mass spectrometry will also be used for the analysis of glycolipids, and new micro methods will be developed. An understanding of the chemical nature of the antigens detected by this panel of antibodies will be essential in understanding their significance and will open the way to future applications of the antigens in diagnosis and therapy.